When operating against the current of traffic, how is a train authorized?

When operating against the current of traffic, a train is authorized using non-signaled DCS rules. This method is employed to ensure safe and effective movement of trains when conventional signaling systems might not apply, especially in scenarios where trains must navigate areas not designed for their direction of travel. Non-signaled DCS (Direct Control System) rules provide the necessary protocols and guidelines for safely directing the train through such conditions.

In contrast, relying on the last signal green light is not applicable here because that signal typically only indicates clear movement in the intended and correct direction of travel. A Dispatcher’s direct order, while critical in many operational contexts, does not specifically pertain to non-signaled DCS scenarios. Lastly, observing physical track signs may provide some guidance, but these signs may not always be set up for or applicable to trains moving against traffic, making them less reliable as an authorization method in those cases.